1. Field of the Invention
The present invention relates to a suspension system for motor vehicles with level regulation for adjusting a predetermined height of the vehicle body including at least one piston-cylinder unit having a work cylinder, a piston rod and a damping piston with damping valves, and a pump for an oil reservoir and corresponding inlet and outlet lines between the oil reservoir and the piston-cylinder unit.
2. Description of the Related Art
Suspensions with automatic level regulation for motor vehicles are already known, for example, from German reference DE 32 12 433 A1 in which the suspension units of the vehicle wheels are supplied from a central oil reservoir via correspondingly open hydraulic lines. Actuating valves are required for connecting the suspension units with the oil reservoir and are supplied with an appropriate amount of oil from the oil reservoir by a central pump. A flow regulator and a height sensor act in the oil circuit when needed to adjust the vehicle body to an appropriate height. The pump is activated for adjusting the height. A disadvantage in a suspension unit of this type is that the hydraulic lines are needed for the forward and reverse flow and the pressureless oil reservoirs require maintenance in that the filling level of the damping medium must constantly be monitored. Further, suspension units of this type cannot be retrofitted in an existing vehicle.
It is an object of the present invention to provide a suspension system with level regulation which is sensed and controlled electrically and which can also be easily retrofitted in existing motor vehicles.
According to the present invention, the object is met by suspension system having a piston cylinder unit including a work cylinder, a piston rod and a damping piston having damping valves. A pump driven by a drive unit is arranged between an oil reservoir and the piston-cylinder unit via inlet and outlet lines, wherein the level height of the vehicle supported by the piston-cylinder unit is detected by a sensor which acts on the drive unit or on a regulating valve via evaluating electronics.
This embodiment allows the vehicle level to be adapted via a sensor and the evaluating electronics, wherein the vehicle body may be regulated either up or down.
The evaluating electronics may be integrated in the drive unit. A compact constructional unit may be provided in this way.
In yet another embodiment form, a regulating valve is integrated in the drive unit. Accordingly, an individual structural component part may be provided which can be flanged to piston-cylinder units which are close in series.
The sensor may be arranged as a component part of the piston-cylinder unit.
According to another embodiment, a throttle or choke is arranged in front of and/or after an outlet valve in the outlet line.
In another embodiment form, the sensor determines the position of the piston rod relative to a housing of the piston-cylinder unit.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.